Controllability measures for disturbance rejection
S. Skogestad and E.A. Wolff

Preprints IFAC workshop on Interactions between process design and process control, London, Sept. 1992, Edited by J.D. Perkins, Pergamon Press, 1992, 23-29 (Reprinted in 1996 in MIC)

Abstract.
Some plants have better "built-in" disturbance rejection capabilities than others, that is, their dynamic resilience (controllability) with respect to disturbance rejection is better. In the paper we consider controller independent disturbance measures for six classes of problems:

  1. Open-loop disturbance sensitivity.
  2. Disturbance sensitivity for decentralized control.
  3. Disturbance sensitivity for system under partial control.
  4. Input magnitude for rejecting disturbances.
  5. Output magnitude for disturbances in the presence of input limitations.
  6. Maximum disturbance range
For all six problems we obtain frequency-dependent measures, and appropriate scaling of the variables is crucial for interpreting these measures. In the paper we also discuss the relationship between these measures and the Relative Disturbance Gain (RDG) of McAvoy and coworkers and the disturbance condition number of Skogestad and Morari.